C.J. Coldon has been ranked as a three-star recruit by Rivals and Scout.com. He was ranked by 247 Sports as the No. 64 overall recruit in the state of Illinois in the 2017 recruiting class. He earned First Team All-State Class 4A honors as a wide receiver from the Illinois Football Coaches Association his senior season at Althoff Catholic High School in Belleville, Ill. He is projected as a cornerback at Wyoming. Coldon was credited with 49 total tackles, including 32 solo tackles as a senior and intercepted two passes for 33 yards. He caught 58 passes for 965 yards and 11 touchdown receptions his senior year, and ranked No. 10 in the state of Illinois in receiving yards (965). Coldon was also utilized as return specialist. His senior season, he had 229 yards in kickoff returns, returning one for a TD, and had 73 yards in punt returns. As a junior, he was credited with 77 total tackles, including 52 solo tackles and added two interceptions for 68 yards, returning both for touchdowns. His junior season, he caught 68 passes for 1,312 yards and 13 TD catches and had 157 combined yards in kickoff and punt return yards, returning a punt for a touchdown and rushing for a TD bringing his touchdown total to 17 TDs his junior season. Coldon ended his high school career with 126 total tackles, including 84 solo tackles and four interceptions for 101 yards. Offensively, he had 126 career receptions for 2,277 yards and caught 24 touchdown passes. He averaged 18.1 yards per reception and 87.6 yards per game for his career. In 2016, Coldon helped lead Althoff Catholic to the quarterfinals of the Class 4A State Playoffs before losing by one point to eventual 4A State Champion Rochester, which featured fellow 2017 Wyoming signee Avante' Cox. Coldon played for head coach Ken Turner.
Coldon was also recruited by Bowling Green, Cincinnati, Iowa, Kansas, Kansas State, Louisville, Miami (Ohio), Missouri, Nebraska, New Mexico and Purdue.